The use of a universal product code (UPC) has gained wide acceptance in the retail industries, particularly in the grocery and food industry, although it is not necessarily so limited in use and can be expected to gain even wider acceptance in the future.
The principle involved is the use of a bar code which uniquely identifies each assigned product by a series of lines and spaces of varying widths which may be decoded to a multiple digit representation. The unique identification is the subject of the UPC and has been standardized for a wide range of products.
At the point of sale, the bar code is read by suitable scanning apparatus and the identification utilized for diverse purposes such as inventory control, pricing, etc., all as is well known.
The use of this bar code has imposed severe problems upon the graphics arts industry whose function is to prepare the labeling, etc., which bears the proper bar code symbol for the product in question. That is to say, the printing of the bar code in mass production normally relies upon a flexographic or an offset printing process from which the widths and spacings of the bar code lines and spaces therebetween must be controlled accurately so that the scanning apparatus may read the bar code with high degree of accuracy. This problem is well known and special apparatus has been developed to aid the graphics art processor in maintaining the requisite quality control. Examples of such apparatus are disclosed in the U.S. Pat. No. 4,360,798 of 11/23/82 to Swartz et al, a divisional application of U.S. Pat. No. 4,251,798, and in U.S. Pat. No. 4,396,361, the disclosures of which are incorporated herein by reference. Basically, what apparatus of this type does is to scan the bar code which has been printed and, in controlled and specified fashion derive a "readability measure" criteria therefrom which apprises the user of the quality of the printed bar code from which adjustments, changes, etc., of the printing process may be made. This "readability measure" is referenced the "Percent Decode" or PD and is based upon many factors which may affect the bar code's symbol readability and which in reality is useful only to the printer. A partial list of these factors includes print contrast, uniform barwidth growth, asymmetric barwidth growth, extent and size of any spots or voids, substrate opacity, showthrough, and scatter. In each case, there exists a transition band over which symbol readability is very strongly affected by small changes in the parameter in question. In theory, there should exist for each parameter an absolute cut off point above which readability is 100%, and below which readability is 0%. However, the algorithm upon which the PD is based generates a "conservative" (insofar as the end user is concerned) statistical value for PD from a single scan, and which PD may be of any value, as low as 10%, for example. This anomaly raises many problems in the industry and has little to do with verifying to the ultimate user the quality of the printed bar code with which he must deal.
The anomaly is created by the fact that the bar codes are checked at locations which are not the end user location, and the end user must therefore blindly accept a product which is represented to him as being of proper quality insofar as readability of the bar code is concerned. As noted, the bar code is normally checked at more than one location. First, the printer checks the bar code which he is printing, usually on a quality control basis during the printing process, and it is here that the system is truly operative, because it enables the printer to take corrective measures in response to deteriorating print quality. However, the absolute value of the PD is of little meaning except as to variations and changes therein (i.e., deterioration), especially as concerns the next person processing the labels to which the bar codes are being applied. That is to say, there is no guarantee that the next processor (the processor who applies the labels to the goods, for example) will read the same PD as did the printer, even though he may be using identical equipment. Thus, this next processor must arbitrarily decide what PD he will establish as being sufficient to meet the needs of the end user.
In this way, whether the end user receives his goods directly from the printer or from a processor applying labels to the goods, he is at the mercy of a guessing game. For example, the printer may check the bar code on a quality control sample basis after the printing process and determine, for example, that the PD is 40%, which the printer may decide will be acceptable to the label applier, and that batch of printed material may be checked by the label applier and found to check with a PD of 20%. This packager must decide whether that value of PD is going to meet the needs of the end user.
The variation in PD may be due entirely to the fact that the printer used one apparatus for checking whereas the packager used another apparatus, even though both were identical in make and type of apparatus and thus ostensibly identical as to result. On the other hand, the variation may also be due to the fact that the apparatus attempts to simulate, based upon a single scan, the statistical average of many different scans having different orientations of the bar code relative to the scanning head. Since neither used an apparatus which is the same as the scanning apparatus which will be used at the point of end use, say the checkout counter scanner at a supermarket, the PD determined either by the printer or the subsequent packager has little if any significance to the end user and may, in fact, confer little or no confidence to the end user that the bar code as scanned and determined at the point of use will be adequate for the intended purpose. Since the end user will suffer from any error in reading of the bar code (whether the error is due to an incorrect number being read or no number being read), the current situation is entirely inadequate insofar as the end user is concerned.
To summarize the background of this invention to this point, great difficulty is encountered in the process of printing bar codes, packaging goods with the bar code readable thereon and accurately reading the bar code on the packaged goods at the point of sale. Many variables are involved in this chain of the process. First of all, the readabilty of the bar code at the point of sale depends upon the quality control of the printing process. Secondly, the bar code must be readable at each potential point of sale. Because the scanning laser device at each point of sale may "see" the bar code in its own unique way which may be different from what will be "seen" at any other similar device at any other point of sale, a tremendous difficulty is encountered because of this factor alone.
At any point of sale, two important factors in reading the bar code are critical. First and foremost, the correct UPC number must be read, otherwise the entire purpose of using UPC designation is lost. Secondly and by no means of lesser importance, reading should be successful upon the first scan of the bar code, otherwise the rapidity and proper flow of tallying the results of scanning and reading at the point of sale is seriously affected.
Thus, the mere fact that the bar code is readable on the first scan is not sufficient unless that read corresponds with the correct UPC number which that bar code is supposed to represent. On the other hand, if it takes more than one scan of the bar code to produce a UPC number output, that output must be the correct UPC number. That is to say, it is imperative that the first successful "read" corresponds with the correct UPC number.
The results of quality control at the steps in the chain prior to the ultimate and final scan of the bar code absolutely determines the success of the entire system.